CATALYSIS LETTERS
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2020
·Vol. 151
·期 6
·1810-1820
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IF 2.482
Zhao Nannan,Wang Songbo,Cheng Penggao,Zhang Jianping,Zhang Lei,Du Wei,Tang Na
Co 3− x Mn x O 4 is a bimetal oxide with excellent electrochemical activity in alkaline solution, has been regarded as a promising alternative in the field of ion-air batteries and proton exchange membrane fuel cell (PEMFC). Herein, we report a simple solvothermal-calcination method to fabricate Co 3− x Mn x O 4 with tunable external Co 3+ /Co 2+ and Mn 3+ /Mn 2+ ratio. The tunable ratio of element valence in the bimetal results in a higher exposure of active center for oxygen redox reaction (ORR), and thus lead to a better ORR activity, which was confirmed by X-ray photoelectron spectroscopy characterizations and electrochemical measurements. Specially, Co 1.8 Mn 1.2 O 4 with a Co 3+ /Co 2+ ratio of 2.08 showed an overpotential of 0.37 V at benchmark ORR current density of 3 mA/cm 2 in 0.1 M KOH, which is lower than that of pure oxide (Mn 3 O 4 0.53 V and Co3O4 0.56 V). In addition, the as prepared Co 1.8 Mn 1.2 O 4 exhibited a positive half-wave potential (0.83 V vs RHE) due to their more active sites, promotes charge transfer, adsorption and desorption of oxygen species. This work provides a strategy for the design and fabrication of earth-abundant, low-cost electrocatalysts for PEMFC in practical applications. Graphic Abstract Co 3− x Mn x O 4 was fabricated by tuning external Co 3+ /Co 2+ and Mn 3+ /Mn 2+ ratio, and the activity initially shows a positive correlation with the ration of Co 3+ /Co 2+ in Co 3− x Mn x O 4 .
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JOURNAL OF MOLECULAR STRUCTURE
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2021
·
IF 3.196
Jiongquan Chen,Zhihua Yang,Kui Wu,Yun Yang,Shilie Pan
A new mixed borate and carbonate Sr 5 (CO 3 ) 2 (BO 3 ) 2 , which is isostructural with Ba 4 M(BO 3 ) 2 (CO 3 ) 2 (M = Ba, Sr), has been synthesized by hydrothermal method . It crystallizes in Pnma (No. 61) space group with the lattice parameters a = 7.387(4), b = 16.556(9) and c = 8.971(5) Å ( Z = 4). This structure features a three-dimensional (3D) network including SrO 8 polyhedra, isolated BO 3 and CO 3 triangles. UV-Vis-NIR diffuse reflectance spectrum for Sr 5 (CO 3 ) 2 (BO 3 ) 2 indicates that it has a deep ultra-violet cut-off edge of 190 nm. In addition, crystal structural comparison among mixed borates and carbonates shows that the interaction between boron-oxide groups and CO 3 groups leads to different arrangements of anionic groups, which can be classified into three types according to the connection of boron-oxide groups. An analysis of theoretical calculations based on density functional theory was also performed to understand the relationships between the structures and properties.
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INORGANIC CHEMISTRY
·
2024
·
IF 4.3
Yuan Lin,Rong-Fang Zhang,Yucheng Hao,Ming-Yang Cao,Xuanlin Pan,Jiang-Gao Mao
Carbonates are ideal birefringent materials because their π-conjugated [CO3] groups are beneficial for large anisotropy. How to maximize the birefringence and maintain a wide transmittance simultaneously in carbonates is a great challenge. Adopting a multiple-functional group synergy strategy by combining alkaline-earth metal Ba2+ with large ion radius, PbO6F distorted hexagonal pyramid, and paralleled π-conjugated CO3 triangles together, we synthesized a new metal carbonate crystal, BaPb2(CO3)2F2. BaPb2(CO3)2F2 features a typical two-dimensional layered structure, which consists of a PbCO3F monolayer parallel to the ab plane and Ba2+ cations filled between the monolayers. BaPb2(CO3)2F2 exhibits a large experimental birefringence of approximately 0.245@546 nm and a short ultraviolet absorption edge down to 264 nm (Eg = 4.70 eV), indicating that it is a promising ultraviolet birefringent material. The reported highest experimental birefringence index among carbonate crystals is surpassed by BaPb2(CO3)2F2. The theoretical calculation shows that the contribution percentages for total birefringence are 57 and 43% for the CO3 group and PbO3F group, respectively. Our work offers a new route for designing new birefringent materials with excellent comprehensive performance.
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PubMed
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JOURNAL OF LUMINESCENCE
·
2015
·
IF 2.719
Dafeng Zhang,Xipeng Pu,Sun Il Kim,Peiqing Cai,Cuili Chen,Hyo Jin Seo
Na 4 La 2−2 x Tb 2 x (CO 3 ) 5 ( x =0–0.5) nanophosphors were prepared via hydrothermal method , and the photoluminescence , concentration quenching, luminescence color chromaticity and thermal activation energy of samples were measured. The results indicate that samples with x values of 0–0.5 possess the pure monoclinic phase with an absorption edge at 250 nm. Na 4 La 2−2 x Tb 2 x (CO 3 ) 5 ( x =0–0.5) phosphors exhibit green luminescence, attributed to the 5 D 4 → 7 F J ( J =6, 5, 4, 3) transitions of Tb 3+ . The concentration quenching takes place at about x =0.3, but no decreased luminescence intensity is observed; moreover, the activation energy of thermal quenching of Na 4 LaTb(CO 3 ) 5 nanophosphor was calculated to be 0.116 eV. The luminescence properties of Na 4 La 2−2 x Tb 2 x (CO 3 ) 5 are benefited from its structural characteristics: long distance between Tb 3+ ions and the ordered distribution of Tb 3+ ions.
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OPTICAL MATERIALS
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2021
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IF 3.08
Dechuan Li,Gungping Zhu,Xuelian Zhao
KTb(CO 3 ) 2 :Eu 3+ phosphors with intense stokes emission were synthesized by hydrothermal method . Under the excitation of 368 nm light, the pure KTb(CO 3 ) 2 shows an intense green emission at 543 nm corresponding to the 5 D 4 → 7 F 5 transition of Tb 3+ , about 5 times higher than that of the K + -free Tb 2 O(CO 3 ) 2 phosphor. As the Tb 3+ is partly substituted by Eu 3+ , the luminescence color can be transformed from green to red. The intensity of red emission of KTb(CO 3 ) 2 :Eu 3+ could greatly increase as the contents of Eu 3+ without any concentration quenching. Under the excited by 368 nm near-ultraviolet, the quantum efficiencies of KTb(CO 3 ) 2 and KTb(CO 3 ) 2 :0.3Eu 3+ were 93% and 80%, respectively. The high quantum efficiency shows that KTb(CO 3 ) 2 :Eu 3+ is a useful color-tunable luminescence material under excitation of ultraviolet light in the anti-counterfeiting, lighting and display.
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Materials
·
2018
·Vol. 11
·期 5
·791
·
IF 2.467
Junping Ding,Huanchun Wang,Haomin Xu,Lina Qiao,Yidong Luo,Yuanhua Lin,Cewen Nan
High efficiency photocatalyst Bi2O2(CO3)1−xSxwas synthesized conveniently with chemical bath precipitation using Bi2O2CO3as the precursor. The microstructures of the samples are systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and UV-Vis spectroscopy; the optical and photocatalytic properties are carefully tested as well. The content ofS, which was tuned through the controlling of the precipitation process, was verified to have an intense effect over the photocatalytic properties. A nearly saturatedSratio and the best photocatalytic performance were observed in specimens with the mostScontent. Our study reveals that, with negligible influence of the morphology and crystal structure, Bi2O2(CO3)1−xSxpossessed a broadened optical absorption regionfromultraviolet to visible light, and enhanced photocatalytic activity in comparison to precursor Bi2O2CO3in photocatalytic degradation of Congo Red aqueous solution.Keywords:Bi2O2CO3;Bi2O2(CO3)1−xSx;broadband spectra;photocatalysis
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2022
·
IF 7.139
Guangkai Guo,Dazhong Zhong,Tao Zhao,Guang Liu,Jinping Li,Qiang Zhao
In recent years, transition metal catalysts due to their low price, excellent conductivity and high activity have been extensively studied in OER . It is worth noting that Co 3+ plays a vital role in the process of oxygen evolution catalysis, because Co 3+ ions are considered to be active sites. The development of catalysts with high Co 3+ content has important application prospects for improving water oxidation efficiency. This paper uses a simple ligand-assisted synthesis method to promote the transformation of two-dimensional layered double hydroxides (LDHs) into two-dimensional metal organic frameworks (MOFs). MOF-OH/NF are quickly and easily prepared by electrooxidation , which exhibit superior OER properties, with a low overpotential of 260 mV and 420 mV for the oxygen evolution reaction (OER) at 100 mA cm −2 and 1000 mA cm −2 . Moreover, the MOF-OH/NF has good stability in 1.0 M KOH electrolyte solution . This study provides a new idea for the design and synthesis of novel composite electrocatalysts .
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JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
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2021
·
IF 6.064
Ying Yang,Kai Chen,Liang Huang,Min Li,Taiping Zhang,Mi Zhong,Ping Ning,Junya Wang,Shikun Wen
It has been reported that the addition of graphene oxide (GO) can increase the dispersion and heterogeneous nucleation of layered double hydroxide (LDH), thus providing more active sites, which is more conducive to CO 2 adsorption. Herein, we reported alkali metal nitrates ((Li 0.3 Na 0.18 K 0.52 )NO 3 ) promoted LDH and GO composites (LDH/GO) as adsorbents for CO 2 capture. The influence of mass ratio of LDH to GO, the impregnation ratio of alkali metal nitrates, the calcination and adsorption temperature, as well as the cycling stability were investigated systematically. The results indicated that the CO 2 capture capacity of LDH/GO composite with 30 mol% (Li 0.3 Na 0.18 K 0.52 )NO 3 could reach 4.51 mmol·g −1 , which was 5.86 times higher than LDH/GO1 without loading alkali metal nitrates. Moreover, it had outstanding CO 2 adsorption capacity in the range from 200 °C to 320 °C. In addition, the cyclic adsorption and desorption test manifested that the CO 2 uptake of the material can reach 3.07 mmol·g −1 after 22 cycles. We believe that this study will give a significant contribution to fabrication of LDH based composites as CO 2 adsorbents in future study.
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JOURNAL OF PHYSICS D-APPLIED PHYSICS
·
2022
·Vol. 55
·期 42
·424005
·
IF 3.409
Chang Wang,Ran Duan,Xingcheng Xiao,Yingwei Wang,Zhihui Chen,Yejun Li,Si Xiao,Jun He
Long hexagonal Co3(PO4)2·4H2O nanosheets were synthesized using a hydrothermal method, where their nonlinearity was probed via a femtosecond Z-scan system. The results show that the Co3(PO4)2·4H2O nanosheets exhibit saturable absorption when the incident photon energy is greater than the forbidden band width, while optical limiting is found when the incident photon energy is smaller than the forbidden band width. In particular, the obtained Co3(PO4)2·4H2O nanosheets demonstrate the best optical limiting properties at 600 nm. The present study suggests the cobalt phosphates nanosheets as a promising candidate for optical limiters.
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Minerals
·
2021
·Vol. 11
·期 11
·1214
·
IF 2.644
Shi Zhou,Yuebo Wang,Henry Teng
Carbonate mineralization is reasonably well-understood in the Ca–CO2–H2O system but continuously poses difficulties to grasp when Mg is present. One of the outstanding questions is the lack of success in dolomite MgCa(CO3)2crystallization at atmospheric conditions. The conventional view holds that hydration retards the reactivity of Mg2+and is supported by solvation shell chemistry. This theory however is at odds with the easy formation of norsethite MgBa(CO3)2, a structural analogue of dolomite, leading to the premise that crystal or molecular structural constrains may also be at play. The present study represents our attempts to evaluate the separate contributions of the two barriers. Crystallization in the Mg–Ba–CO2system was examined in a non-aqueous environment and in H2O to isolate the effect of hydration by determining the minimal relative abundance of Mg required for norsethite formation. The results, showing an increase from 1:5 to 6:4 in the solution Mg/Ba ratio, represented a ~88% reduction in Mg2+reactivity, presumably due to the hydration effect. Further analyses in the context of transition state theory indicated that the decreased Mg2+reactivity in aqueous solutions was equivalent to an approximately 5 kJ/mol energy penalty for the formation of the activated complex. Assuming the inability of dolomite to crystallizes in aqueous solutions originates from the ~40 kJ/mol higher (relative to norsethite) Gibbs energy of formation for the activated complex, a hydration effect was estimated to account for ~12% of the energy barrier. The analyses present here may be simplistic but nevertheless consistent with the available thermodynamic data that show the activated complex of dolomite crystallization reaction is entropically favored in comparison with that of norsethite formation but is significantly less stable due to the weak chemical bonding state.Keywords:norsethite;dolomite;transition state theory;activated complex;crystallization barrier;hydration
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2026
·
IF 9.2
Shuhua Li,Yaxing Li,Shilin Liu,Hao Ye,Yuxiu Wang,Yu Xie,Jiansheng Zhang
ZnIn 2 S 4 is a highly promising photocatalyst, but its rapid carrier recombination remains the core bottleneck. Constructing band-matched heterojunctions to promote charge separation is currently the most effective strategy to address this issue. Herein, a Co 3 (PO 4 ) 2 /ZnIn 2 S 4 (CPO/ZIS) type-II heterojunction photocatalytic system is designed. The intimate coupling between CPO and ZIS is achieved via electrostatic self-assembly. Studies show that this system follows a type-II charge transfer mechanism, and owing to the strong affinity of phosphate groups for protons in aqueous solution and the electron-trapping function of cobalt active centers, the hydrogen production efficiency is synergistically enhanced. The optimal 10-CPO/ZIS composite achieves a HER of 8.87 mmol g −1 h −1 , which is 8.53 times that of pristine ZIS, and also exhibits excellent photocorrosion resistance.
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ACS Applied Energy Materials
·
2020
·
IF 4.473
Yun-lei Zhong,Zhen-jiang Yu,Li-tong Wang,Tao Liang,Xuetong Zhang,Guo Hong
Lithium ion batteries are the most feasible energy storage technology for modern society. However, the electrochemical performance of commercial products is not satisfactory, which severely limits the development of electrode materials. An urgent call to balance the demands of high surface area, rich site activity, enhanced electrical conductivity, and controlled electrochemical stability becomes even more desired. In this work, we report a Co3O4 hexagonal prism (CHP) with a unique anisotropy structure as the anode material for lithium ion storage. Specifically, the CHP has a solid microframework on the six sidewalls and porous nanotunnels on the top and bottom surfaces, which not only enhances lithium ion storage and transmission but also provides sufficient electrochemical stability (i.e., minimize volume expansion). Additionally, it has much higher Co3+ contents and oxygen vacancies on all the surfaces which contribute to rich site activity and enhanced electrical conductivity. Based on these, the anisotropy CHPs show a remarkably higher initial capacity, excellent rate capability, and unique cycling stability than those of Co3O4 nanowires and commercial Co3O4 microparticles. The resulting CHP electrodes demonstrate an excellent reversible capacity of 800 mA h g–1 after 800 cycles at 1 A g–1. A further mechanistic study reveals the relationship between the material properties and the electrochemical performances, which can be mainly attributed to the synergistic effect of the anisotropy architecture, the surface pseudocapacitance, and the enriched Co3+ on the material surface. This synthetic strategy provides insights for the development of high-performance anodes.
研究领域:
材料科学
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储能
·
电化学
·
纳米材料
·
锂离子电池
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